Abstract
Preparations of new low molecular weight protein inhibitors of serine proteinases have been obtained from buckwheat Fagopyrum esculentum seeds by chromatography of seed extracts on trypsinSepharose 4B, MonoQ and MonoS ionexchangers. Their molecular masses, determined by mass spectrometry, were equal to 5203 (BWI-1c), 5347 (BWI-2c), 7760 (BWI-3c) and 6031 daltons (BWI-4c). All inhibitors possessed high pHstability in the pH range 212 and thermostability. In addition to trypsin, BWI-3c and BWI-4c inhibitors inhibited chymotrypsin and subtilisinlike proteases. The inhibition constants (K) for trypsin, chymotrypsin and subtilisin by the studied inhibitors were determined. The Nterminal sequences of all inhibitors were established: BWI-1c (23 residues), BWI-2c (33 residues), BWI-3c (18 residues) and BWI-4c (20 residues). According to the physicochemical properties and Nterminal amino acid sequences, buckwheat seed protease inhibitors BWI-3c and BWI-4c are suggested to belong to the potato proteinase inhibitor I family.
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